In recent years, it has been demanded that a notebook-size personal computer (hereinafter referred to as the notebook-size PC) be further compact and light. The notebook-size PC is carried under a user's arm, received together with documents and the like in a bag, or provided with the documents laid thereon on a desk. Therefore, a casing of the notebook-size PC is required to have such a mechanical strength as to protect inner (e.g. electronic) components against a pressing force from the outside. In particular, the center of a display casing accommodating a liquid crystal display is brittle and needs protection. Therefore, when the center of the closed display casing is pressed, an influence such as strain is left in a screen displayed in the liquid crystal display. Moreover, the center of the display casing easily comes in contact with a keyboard or a portion around the keyboard, and is easily damaged. Therefore, in particular, a sufficient strength against the pressing force applied to the center of the casing needs to be secured.
For example, there are the following conventional technologies concerning a reinforcing structure concerned with display. Japanese Patent Application Laid-Open No. 8-76886 teaches a technology in which a liquid crystal display casing is fixed together with a lid casing attachment portion of a lid casing so as to be freely opened and closed through hinges, and the lid casing is reinforced by a reinforcing plate subjected to squeeze processing. Japanese Patent Application Laid-Open No. 9-62400 teaches a technology in which a brace-like rhombic lattice rib is arranged between the back surface cover of the notebook-size PC and the liquid crystal display to increase the strength of the back surface cover. The back surface cover accommodates the liquid crystal display and a fluorescent tube, and is connected to an input section via hinges. Japanese Patent Application Laid-Open No. 2001-134195 teaches a technology in which a laminated panel holding a honeycomb core made of an aluminum alloy between aluminum alloy plates is provided on the back surface, to improve earthquake-proof properties of a plasma display device.
These and other conventional solutions have significant shortcomings and have not sufficiently addressed the need for a compact and light casing that provides the necessary (e.g. protective) functions.